import pandas as pd
df =pd.DataFrame({'商品':['苹果','香蕉','梨'],
                  '单价(元)':[5,5,4],
                  '销量(kg)':[100,None,None],
                  '库存(kg)':[50,None,70]
                  })
print('原始数据:\n',df)
print('删除包含缺失值的行:\n',df.dropna())
print('删除包含缺失值的列:\n',df.dropna(axis=1))
print('删除少于3个非列缺失值的行:\n',df.dropna(thresh=3)
)
print('删除库存列包含列缺失值的行:\n',df.dropna(subset=['库存(kg)'])
)

print('删除少于2个非列缺失值的行:\n',df.dropna(thresh=2)

print('删除销量列包含列缺失值的行:\n',df.dropna(subset=['销量(kg)'])
)